iOS頁面間傳值的方式（Delegate/NSNotification/Block/NSUserDefault/單例）

2019-11-14 20:14:30

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iOS頁面間傳值的方式（NSUserDefault/Delegate/NSNotification/Block/單例）

實現了以下iOS頁面間傳值：1.委托delegate方式；2.通知notification方式；3.block方式；4.UserDefault或者文件方式；5.單例模式方式；6.通過設置屬性，實現頁面間傳值

在iOS開發中，我們經常會遇到頁面間跳轉傳值的問題，現歸納總結一下：

情況1：A頁面跳轉到B頁面

方法：

在B頁面的控制器中，編寫對應的屬性，在A頁面跳轉到B頁面的地方，給B的屬性賦值即可

//SecondViewController.h


@PRoperty(nonatomic) NSInteger flag;//當前系統標示（0：其他傳值方式；1：block傳值方式）

在A頁面的試圖控制器中

//RootViewController.m


- (IBAction)showSecondView:(id)sender {    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];    second.delegate = self;    second.flag = 0;    [self presentViewController:second animated:YES completion:nil];}

情況2：A頁面跳轉到B頁面，B頁面再跳轉回A頁面

主流方案：

（1）通過委托delegate的方式實現

設置協議及方法

//SecondViewController.h


@protocol secondViewDelegate-(void)showName:(NSString *)nameString;@end

設置代理(為防止循環引用，此處采用了weak)

//SecondViewController.h


@interface SecondViewController : UIViewController@property (nonatomic, weak)id<secondViewDelegate> delegate;@property (nonatomic, copy) ablock block;@end

調用

//SecondViewController.m
- (IBAction)delegateMethod:(id)sender {    if ([self notEmpty]) {        [self.delegate showName:self.nameTextField.text];        [self dismissViewControllerAnimated:YES completion:nil];    }else{        [self showAlert];    }}

顯示

//RootViewController.m
-(void)showName:(NSString *)nameString{    self.nameLabel.text = nameString;}

最重要也是最容易忽略的，就是一定要設置delegate的指向。

（2）通過通知notification的方式實現

在B頁面的控制器中，發送通知：

//SecondViewController.m- (IBAction)notificationMethod:(id)sender {    if ([self notEmpty]) {        [[NSNotificationCenter defaultCenter] postNotificationName:@"ChangeNameNotification" object:self userInfo:@{@"name":self.nameTextField.text}];        [self dismissViewControllerAnimated:YES completion:nil];    }else{        [self showAlert];    }}

在A頁面的控制器中，注冊通知：

//RootViewController.m- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view from its nib.    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(ChangeNameNotification:) name:@"ChangeNameNotification" object:nil];}

當我們不使用時，要記得刪掉通知：

//RootViewController.m-(void)dealloc{    [[NSNotificationCenter defaultCenter] removeObserver:self];}

調用，顯示

//RootViewController.m-(void)ChangeNameNotification:(NSNotification*)notification{    NSDictionary *nameDictionary = [notification userInfo];    self.nameLabel.text = [nameDictionary objectForKey:@"name"];}

（3）block方式實現

block介紹:http://blog.csdn.net/totogo2010/article/details/7839061

鏈接一篇描述block回調挺有意思的文章： http://blog.csdn.net/mobanchengshuang/article/details/11751671

分析：

在B試圖控制器中，定義一個block，參數為字符串

//SecondViewController.htypedef void (^ablock)(NSString *str);

//SecondViewController.h@property (nonatomic, copy) ablock block;

在B試圖控制器中，當輸入名字，點擊對應的確定按鈕后

- (IBAction)blockMethod:(id)sender {    if ([self notEmpty]) {        if (self.block) {            self.block(self.nameTextField.text);            [self dismissViewControllerAnimated:YES completion:nil];        }    }else{        [self showAlert];    }}

在A試圖顯示，回調block

- (IBAction)showSecondWithBlock:(id)sender {    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];    [self presentViewController:second animated:YES completion:nil];    second.block = ^(NSString *str){        self.nameLabel.text = str;    };}

（4）KVO方式實現

KVO實現原理介紹：http://blog.csdn.net/kesalin/article/details/8194240

在A視圖中，編寫以下代碼

//A視圖//一個指向B視圖的成員變量@property (nonatomic, strong) SecondViewController *second;//在A視圖跳轉到B視圖的地方添加如下代碼    self.second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];    [self.second addObserver:self forKeyPath:@"userName" options:NSKeyValueObservingOptionNew context:nil];    [self presentViewController:self.second animated:YES completion:nil];-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{//此處監聽key對應值的變化情況    if ([keyPath isEqualToString:@"userName"]) {        self.myLabel.text = self.second.userName;    }}//清理觀察- (void)dealloc{    [self.second removeObserver:self forKeyPath:@"userName"];}

在B視圖編寫以下代碼

//在B視圖//.h文件@property (nonatomic, strong) NSString *userName;//待監聽的成員變量//可以在兩處修改userName的值。一個是設置textfield的UITextFieldDelegate。實現一下方法-(void)textFieldDidEndEditing:(UITextField *)textField{self.userName = self.myField.text;}//或者在B視圖，點擊確定按鈕，跳轉回A視圖的時候，修改userName的值也可以- (IBAction)buttonPressed:(id)sender {    self.userName = self.myField.text;    [self dismissViewControllerAnimated:YES completion:nil];}

在查閱資料的過程中，我還看到了以下幾種方案：

（1）使用Sharedapplication,定義一個變量來傳遞（感覺和單例的方式一樣）

（2）使用文件，或者NSUserdefault來傳遞

//通過文件或者UserDefault方式存值(感覺不太適合此類傳值，如果要用文件或者UserDefault方式存值的話，可以考慮此方式)- (IBAction)userDefaultMethod:(id)sender {    if ([self notEmpty]) {        [[NSUserDefaults standardUserDefaults] setObject:self.nameTextField.text forKey:@"myNameText"];        [self dismissViewControllerAnimated:YES completion:nil];    }else{        [self showAlert];    }}

在A試圖控制器顯示

-(void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];    //如果想測試通過UserDefault方式傳值或者通過單例方式傳值，取消以下注釋即可/*    if ([[[NSUserDefaults standardUserDefaults] objectForKey:@"myNameText"] length] != 0) {        self.nameLabel.text = [[NSUserDefaults standardUserDefaults] objectForKey:@"myNameText"];        [[NSUserDefaults standardUserDefaults] setObject:@"" forKey:@"myNameText"];    }    DataSource *dataSource = [DataSource sharedDataSource];    if ([dataSource.myName length] != 0) {        self.nameLabel.text = dataSource.myName;        dataSource.myName = @"";    }*/}

（3）通過一個單例的class來傳遞

B試圖控制器

//通過單例方式傳值(感覺不太適合此類傳值，如果要用單例方式傳值的話，可以考慮此方式)- (IBAction)singletonMethod:(id)sender {    if ([self notEmpty]) {        DataSource *dataSource = [DataSource sharedDataSource];        dataSource.myName = self.nameTextField.text;        [self dismissViewControllerAnimated:YES completion:nil];    }else{        [self showAlert];    }}

A試圖控制器顯示

-(void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];    //如果想測試通過UserDefault方式傳值或者通過單例方式傳值，取消以下注釋即可/*    if ([[[NSUserDefaults standardUserDefaults] objectForKey:@"myNameText"] length] != 0) {        self.nameLabel.text = [[NSUserDefaults standardUserDefaults] objectForKey:@"myNameText"];        [[NSUserDefaults standardUserDefaults] setObject:@"" forKey:@"myNameText"];    }    DataSource *dataSource = [DataSource sharedDataSource];    if ([dataSource.myName length] != 0) {        self.nameLabel.text = dataSource.myName;        dataSource.myName = @"";    }*/}@end

這里面用到了單例模式，編寫了DataSource這個類，存放數據

////  DataSource.h//  TestCallBack////  Created by csdc-iMac on 14-7-17.//  Copyright (c) 2014年 JuneWang. All rights reserved.//#import <Foundation/Foundation.h>@interface DataSource : NSObject@property (nonatomic, strong) NSString *myName;+(DataSource*)sharedDataSource;@end

////  DataSource.m//  TestCallBack////  Created by csdc-iMac on 14-7-17.//  Copyright (c) 2014年 JuneWang. All rights reserved.//#import "DataSource.h"@implementation DataSource+(DataSource *)sharedDataSource{    static DataSource *dataSource = nil;    static dispatch_once_t once;    dispatch_once(&once, ^{        dataSource = [DataSource new];    });    return dataSource;}@end